Surface scanning apparatus and method using crossed-cylinder optical elements
US5565979A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 4, 1994 |
| Grant date | Oct 15, 1996 |
| Priority date | — |
| Expiry date | Nov 4, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/8806
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An apparatus and method for inspecting a substrate, such as a semiconductor wafer, includes crossed cylindrical optical elements that form an elliptical beam that is caused to scan in parallel fashion at an oblique angle to the substrate. Preferably, the smaller dimension of the elliptical beam is perpendicular to the direction of the scan of the beam across the wafer. A reflector converts an angularly varying beam to a telecentrically scanning beam and also provides focusing only in the direction parallel to the telecentric scan. On the other hand, a cylinder lens has a focusing power only in the direction perpendicular to the telecentric scanning.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.